1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine, laser beam printer and the like, and more particularly, it relayes to an image forming apparatus (referred to as "copying machine" hereinafter) which includes a manual sheet feed device and a sheet re-feeding path.
2. Related Background Art
A copying machine including a manual sheet feed device and a sheet re-feeding path has been already known. As shown in FIG. 1, such conventional copying machine 1a has a machine frame 3 including a copying portion 2 therein, and includes a platen 5, a light source 6, mirrors 7-12, a lens 13, and two cassettes 15, 16 for accommodating sheets S therein. Sheet feed rollers 17 and 19 are arranged above the cassettes 15 and 16, respectively. A pair of separating/feeding rollers 21 are arranged downstream of the sheet feed roller 17, and a pair of separating/feeding rollers 21 are arranged downstream of the sheet feed roller 19. Further, a pair of regist rollers 22 are arranged downstream of the roller pairs 20, 21.
In addition, the copying portion 2 is situated downstream of the pair of regist rollers 22, and a feeding device 23 and a fixing device 25 are arranged downstream of the copying portion 2. A feeding roller 24, a flapper 26 and ejector rollers 27 are arranged downstream of the fixing device 25, and an ejector tray 29 is arranged downstream of the ejector rollers 27. Further, a sheet re-feeding path 30 is branched from the flapper 26, which sheet re-feeding path 30 includes pairs of feeding rollers 31, 32 and a pair of re-feeding rollers 33.
Further, the copying portion 2 includes a cylindrical photosensitive drum 42 around which an eraser lamp, a primary charger 45, a color developing device 46, a developing device 47, a transfer charger 49, a separating charger 50 and a cleaner 51 are arranged. A rockable manual sheet feed tray 52 is mounted on a side of the machine frame 2 above the cassette 15. Incidentally, in FIG. 1, the reference numerals 53, 55, 56 denote guide plates.
In case where a one-face or one side copying operation is performed, when a start key (not shown) is depressed, the sheet feed roller 17 or 19 is rotated to pick up the sheet S from the cassette 15 or 16. Then, the sheet S is fed by the pair of separating/feeding rollers 20 or 21 to the regist roller pair 22, and, thereafter, the sheet is fed by the regist rollers 22 to the photosensitive drum 42 in synchronous with an image formed on the photosensitive drum, where the image on the photosensitive drum 42 is transferred onto the sheet by means of the transfer charger 49. Then, the image transferred to the sheet S is fixed on the sheet by means of the fixing device 25. Thereafter, the sheet S is directed by the flapper 26 to the pair of ejector rollers 27 to be ejected on the ejector tray 29.
On the other hand, in case where a both-face copying operation or a multiple copying operation is performed, the sheet S on which the image is transferred in the same manner as mentioned above is directed by the flapper 26 to the sheet re-feeding path 30 through which the sheet is re-fed to the regist rollers 22. Then, the same sheet is subject to the second copying operation and is ejected onto the ejector tray 29.
When the manual sheet feed is effected, an operator opens the manual sheet feed tray 52 and supplies the sheet S along the manual sheet feed tray. In this case, the sheet S is introduced on the uppermost sheet in the cassette 15 and detected by a sensor (not shown). On the basis of a signal emitted from the sensor, the sheet feed roller 17 and separating/feeding rollers 20 are rotated to feed the manually fed sheet S to the regist rollers 22. Thereafter, the manually fed sheet S is subject to the copying operation and is ejected to the ejector tray 29 in the same manner as mentioned above.
By the way, in the above-mentioned conventional copying machine 1a, since the manual sheet feed tray 52 is situated on the right side of the machine frame 3, when the manually fed sheet S is supplied to the manual sheet feed tray 52, it is necessary to maintain an adequate space at the right side of the machine frame 3, thus preventing the saving of the space.
In order to eliminate this drawback, Applicant has proposed a copying machine in which the manually fed sheet can be inserted at a front side of the copying machine.
However, if such copying machine includes the sheet re-feeding path for the both-side copying operation and the multiple copying operation, the addition of the manual sheet feed device makes the copying machine large-sized.